This is a very particular solution to your current setup. A more general solution would be required where the name length and font size could vary. However, without more detail, this should be sufficient.

Also, there is no particular need to use the res class for creating a resume. It is possible to use the default article class to replicate the layout, yet have some additional freedom in terms of the layout. Moreover, moderncv provides a stylish take on resumes as well.